PROJECT SUMMARY The goal of this NRSA individual postdoctoral fellowship is to facilitate Dr. Nilay Shah's development as a leader and independent physician-scientist in atherosclerotic cardiovascular disease (ASCVD) prevention research. With recent reversal of decades of decreasing trends in age-adjusted ASCVD mortality, innovative approaches to identify novel contributors to ASCVD risk are critical. As previous work indicates that a person's health may be influenced by the people with whom one has social contact, Dr. Shah proposes to evaluate the influence of personal social network characteristics on cardiovascular health and ASCVD, specifically in South Asians, who experience a disproportionately high burden of ASCVD and have robust social network structures. Dr. Shah and his mentors have designed a comprehensive plan that builds upon his clinical cardiovascular disease training and research background in cardiovascular epidemiology with the aim of launching his career as an independent investigator. He proposes to develop additional skills during the award period through (1) methodology-focused coursework in social network analysis, qualitative methods, and advanced biostatistics; (2) mentoring by a multidisciplinary team of sponsors and collaborators with complementary expertise in cardiovascular disease epidemiology and prevention, South Asian health, social network-based research, and mixed methods analysis; and (3) a supervised research project that aligns with the National Heart, Lung, and Blood Institute's challenge to investigate factors, including social exposures, that account for differences in health among populations. The scientific objectives of this research project are addressed via two specific aims: (1) to evaluate using epidemiologic methods the associations of personal social network and organizational affiliation network data with cardiovascular health and ASCVD measured by coronary artery calcium in South Asian American participants in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) cohort study, and (2) to characterize using qualitative methods the mechanisms employed by participants in the South Asian Heart Lifestyle Initiative (SAHELI) behavioral intervention trial to disseminate information and health-related behaviors within their social networks. The proposed research project, training, and mentoring team will foster Dr. Shah's proficiency in mixed methodology in cardiovascular epidemiology, evaluation of population-based data, and scientific writing. The goals of this project directly address NHLBI's compelling questions to investigate how social conditions influence ischemic heart disease risk, and how this risk may be managed to improve health trajectories. By leveraging a collaborative research infrastructure to investigate new mechanisms that may contribute to ASCVD development, Dr. Shah ultimately aims to inform prevention strategies and reduce the burden of ASCVD worldwide. Near the end of the award period, Dr. Shah will apply for a Pathway to Independence or similar transition award, using the results of this project to further study the role of social networks and social network-related interventions to improve ASCVD outcomes.